In January 1917, British naval intelligence intercepted a secret telegram from Germany’s foreign secretary, Arthur Zimmermann, offering his country’s support to Mexico for regaining lost territory in the U.S. in exchange for a Mexican attack on the United States. Five weeks later, America entered World War I. This remarkable study taps fresh sources to provide a definitive account of the origins, cryptanalysis, and impact of the German alliance scheme. Challenging many widely accepted views of what happened, the author contends that the telegram was a spontaneous initiative, not the result of a long-term German plan. He further argues that the telegram did not rally Americans for war, but instead proved divisive, alienating isolationist and pacifist groups and lawmakers. He also corrects mistakes made previously about how the telegram was sent and coded. The book’s new findings, as well as a firsthand account of how the telegram was conceived, published here for the first time, are certain to attract attention.

Thomas Boghardt is a senior historian at the U.S. Army Center of Military History in Washington, D.C.

Praise for The Zimmermann Telegram

“In The Zimmermann Telegram, Thomas Boghardt has written one of the most far-reaching examinations of the telegram and its impact. He has done an exceptional service by placing the Zimmermann telegram within the \diplomatic and military context of the war and fully describing all aspects of this event. Overall, this is an outstanding book. With the centennial of World War I upon us, interest in the Zimmermann telegram will no doubt increase. For those who wish to know the full story, one must only turn to this book for a definitive treatment.”

—Army History

“Replete with deft pen portraits of the main protagonists such as Kemnitz—nicely characterized by Hollweg’s secretary, Riezler, as a ‘fantastic idiot’—Boghardt has produced a highly readable, scholarly, and accomplished account. It adds particularly to our understanding of the dysfunctional nature of German policy-making.”

– The Historian

“A specialist in the history of espionage and covert operations during the Great War, in The Zimmermann Telegram Boghardt gives us the first new book on this event since Barbara Tuchman’s treatment over 60 years ago. In his excellent opening survey of the historiography of the subject, Boghardt notes that Tuchman and other earlier writers on the subject worked without many documents that remained classified until recently, and also wrote largely without reference at all to German sources. A valuable work for anyone interested in the diplomacy of the war or American’s participation.”

"A valuable work for anyone interested in the diplomacy of the war or American’s participation."

– The NYMAS Review

“In a well-documented and closely argued text, the author draws on documents not available at the time Barbara Tuchman’s classic work was written in 1957 and takes a fresh look at the Zimmermann fiasco.”

– Stand To!, The Western Front Association

“Thomas Boghardt mined an important lode of new material for his history not previously available to historians. In doing so, he has created a notable retelling of this story that should be studied and enjoyed by anyone looking to understand this key moment in modern history.” – H-net.org

"Overall, this is a deeply researched, clearly written, and highly analytical monograph. It certainly supersedes anything else written on the Zimmermann telegram and should be read by anyone interested in the First World War."

— Intelligence and National Security, 2013

“…Fascinating book.”

— Military History, July 2013

“...The story of the Zimmermann telegram has enough twists and turns to keep the attention of even a jaded James Bond. U.S. Army Center of Military History senior historian Thomas Boghardt is a thoughtful, technically astute, balanced investigator and fine author of prose…Read TheZimmermann Telegram. You won’t be disappointed.”

“U.S. Army Center of Military History senior historian Thomas Boghardt is a thoughtful, technically astute, balanced investigator and fine author of prose…Read The Zimmermann Telegram. You won’t be disappointed.”

— Naval Historical Foundation

“Boghardt blends the scholarship of a refined historian with the narrative skills of a John Le Carré in retelling the story of the Zimmermann telegram. Summing Up: Highly recommended.”

— Choice, May 2013

“…Should be the definite work on the subject…Dr. Boghardt’s work is a masterpiece of intelligence writing. By following the hard evidence rather than relying on historical assumptions, he provides an incisive case study on how intelligence can affect national affairs.”

"This is a fresh, comprehensive study of how intelligence and counter-intelligence can be used in war, and of an incident that formed one of the markers on the way to the special relationship between Britain and the USA."

"The detailed analysis here, drawing from documents of the time, tells us much that is new about the telegram, its decryption, and the tricks which not only brought it to light in 1917 but also kept the whole story from being told until now."

"Boghardt expertly dissects the political and military situation surrounding the decrypt ion and dissemination of the notorious Zimmermann Telegram which triggered (but was not the cause) America's entry into the Great War. Of equal importance are his brief but revealing character sketches of the principal actors in the drama: German Foreign Secretary Arthur Zimmermann, British naval intelligence chief, William "Blinker" Hall, Wilson confidant Colonel Edward House, and U.S. Secretary of State Robert Lansing among many other major and minor characters."

"The Zimmermann Telegram will fascinate history buffs. It is worth reading."

—Galveston Daily News, 18 November 2012

“Thomas Boghardt has written the only book anyone needs to read about the storied Zimmermann Telegram episode. By exhaustively mining several countries’ archives, using previously unavailable records, and giving equal treatment to all the major players, Boghardt corrects many durable misunderstandings about how the telegram was conceived, discovered, perceived, and exploited. He has made a vital contribution to the scholarship on intelligence and World War I.”

—David Robarge, chief historian, Central Intelligence Agency

“The Zimmermann Telegram is a critical moment in the history of World War I and the history of intelligence. Thomas Boghardt’s work deftly examines the disclosure of the telegram, the U.S. entry into the war, and its historical memory. It’s a lovely work of scholarship, deeply researched, that pays careful attention to all the main actors and reads as compellingly as a thriller.”

—David Silbey, author of The British Working Class and Enthusiasm for War, 1914?1916 and The Boxer Rebellion and the Great Game in China, 1900

“Boghardt has given us a deeply researched and well-written book that tells us much that is new about the Zimmermann Telegram and its role in American entry into World War I. More than that, however, it is a solid analysis of German foreign policy and the international context of 1917. It should be a must read for anyone interested in these subjects.”

—Michael S. Neiberg, author of Dance of the Furies: Europe and the Outbreak of World War I

“Thomas Boghardt has provided the most thorough, comprehensive, and reliable account to date of the Zimmermann Telegram. He has judiciously analyzed the diplomatic, political, bureaucratic, and cryptological dimensions of the crisis. His conclusions about its role in the American decision to enter the war against Germany in 1917 are compelling.”

—Roger Chickering, professor emeritus, Georgetown University, and author of Imperial Germany and the Great War, 1914–1918

“Thomas Boghardt has produced a brilliant analysis of the most sensational code-breaking coup of World War I which also sheds new light on the origins of today’s British-American special relationship.”

—Christopher Andrew, author of Defend the Realm: The Authorized History of MI5